1. Field:
This invention relates to processes for recovering bituminous organic material from tars sands or oil sands, and, more particularly, to processes utilizing an organic solvent to dissolve the bituminous material from the sands.
2. State of the Art:
Large deposits of oil sands or tar sands are found in various parts of the world, in particular in Canada, the United States of American, Venezuela, Russia, and Malagasy. Various attempts have been made in the past to recover the bituminous organic material from tar sands and oil sands. Retorting and other thermal processes are uneconomical due to the large quantity of heat consumed without any effective and efficient recovery thereof.
Processes utilizing water and a hydrocarbon diluent, such as kerosene, have been disclosed. For example, see U.S. Pat. Nos. 2,453,060; 2,825,677; and 3,509,037. Unfortunately, such processes utilize large amounts of heat and water. In addition, these processes are expensive and can cause serious environmental problems due to polluted water and sand which are produced in copious amounts.
Solvent extraction of bituminous organic material from tar sands or oil sands has also been proposed. For example, see U.S. Pat. Nos. 1,514,113; 2,453,633; 2,596,793; 3,050,289; 3,079,326; 3,131,141; 3,392,105; 3,475,318; 3,503,868; 3,509,037; 4,029,568; 4,046,668; 4,046,669; 4,057,485; and 4,110,194. Unfortunately, low yields, high energy consumption, loss of solvents, and environmental problems including dirty spent sands containing both solvent and bituminous material has hindered the development the solvent extraction processes.
3. Objectives:
A principal objective of the present invention is to provide an efficient solvent extraction process for high yields of bituminous organic material from tar sands or oil sands with a low solvent loss. Another objective of the invention is to develop a process requiring a minimum of energy consumption due to the relatively mild conditions used in recovering the organic solvent from the bituminous organic material and the effective recovery and reuse of heat values. A further objective of the invention is to provide a process which uses only very small amounts of water. An even further objective of the invention is to provide a process which is environmentally clean, i.e., can be operated without polluting the ambient air and water, and produces a clean sand which can be further processed to recover mineral values therefrom or disposed of without causing a pollution problem. A still further object of the invention is to provide a process for efficiently recovering the bituminous organic material in a form which can be used for many purposes without further processing or treatment.